We have lately heard much of the claim that 2010 will turn out to have been “the hottest year on record”. No one has done more to promote this belief than Dr James Hansen, head of Nasa’s Goddard Institute for Space Studies (GISS), responsible for one of the four main official global temperature records.

As reported by the US blogs Real Science and Watts Up With That, in a post headed “GISS temperatures out of line with the rest of the world”, the GISS record has in recent months been diverging wildly from the others. While three have shown global temperatures dropping sharply, by as much as 0.3C, the GISS figures (based, despite the link to Nasa, on surface temperatures) have shot up by 0.2C.

In a second post (“Hansen’s ‘Hottest Year Ever’ is primarily based on fabricated data”), Real Science demonstrates that the parts of the world which GISS shows to be heating up the most are so short of weather stations that only 25 per cent of the figures are based on actual temperature readings.

The rest are simply conjectured by GISS. This is not the first time Dr Hansen’s temperature record has come under expert fire. Three years ago, GISS was forced to revise many of its figures when it was shown that wholesale “adjustments” had been made, revising older temperatures downwards and post-2000 figures upwards.